Update SECURITY.md (#168)

Add org-wide disclaimer regarding sample and example code

Author: geoffg-sentry

SECURITY.md

@@ -18,3 +18,8 @@ If you need to encrypt sensitive information sent to us, please use [our PGP key
 ```
 E406 C27A E971 6515 A1B1 ED86 641D 2F6C 230D BE3B
 ```
+
+## Example and Sample Code
+
+> [!WARNING]  
+> Unless otherwise specified, example and sample code in our repos is unmaintained. Sample code may contain security vulnerabilities, should never be used in production, and exists only for illustrative purposes.